The aerodynamics of helicopters is highly complex. Due to the rotation of the rotors the flow is always unsteady and it features various flow phenomena. For a helicopter in forward flight the flow on the advancing rotor blade experiences transonic effects, while on the retreating blade dynamic stall may occur. The wakes of the rotor blades interfere significantly with the other rotor blades. The flow about the fuselage and the empennage of the rotorcraft has a high impact on flight performance and handling characteristics.
The objective of the department helicopters is to study the physics of helicopter flows as well as to optimize the aerodynamic and aeroacoustic characteristics of helicopters. The research contributes to increasing the performance of the helicopters and to reducing their environmental footprint in terms of exhaust and noise emissions.
The research contributes to the understanding of the relevant flow phenomena of unsteady, rotating flows
Development and adoption of modern measurement techniques for aerodynamic experiments in wind tunnel and flight tests.
Extension and validation of the CFD solvers under development at the Institute for Aerodynamics and Flow Physics to helicopters. A focus is the highly accurate prediction of the flow about rotors and complete helicopter configurations. A multidisciplinary simulation approach with high-fidelity simulation methods including a Fluid-Structure-Trim-coupling is mandatory to resolve the relevant flow features and to consider the significant motion of the rotor blades. The motion of the rotor blades is not only prescribed by the pilot, but is also affected significantly by the aerodynamic forces, the rotor’s dynamic behavior and the elastic deformations of the blades.
Aerodynamic Design and Optimization of helicopters to increase flight performance and to reduce drag. The challenge in helicopter design is to consider all the various flight states of helicopters with partly contradicting design requirements for example hover and forward flight. The development of multidisciplinary multipoint design- and optimization-tools is therefore an important part of the research.
The research in helicopter aeroacoustics aims at understanding the noise sources of helicopters and developing technologies to reduce the noise emission of helicopters. The research includes the development and application of numerical methods for the acoustic analysis and design as well as flight tests.
Next to the activities for rotorcrafts the department helicopters is involved in two additional research activities:
Research aims at procedures for the prediction of aircraft noise pollution and the development of computer models which can be used as part of these procedures. In addition the group acts in an advisory capacity to public authorities, the aviation industry and interest groups as well as providing general advice about aircraft noise questions.
Research for wind turbines aims at improving their aerodynamic efficiency and at increasing the reliability of load prediction. This requires to consider the realistic operational conditions, for example the realistic atmospheric inflow, the elastic deformation of the rotor blades, and the controller. The development of highly accurate, multidisciplinary simulation and optimization chains is therefore an important part of the research.